There exist currently a wide variety of systems for controlling the delivery of various forms of power. Among these power delivery systems for example are isolation systems that are designed to disconnect, ground and/or otherwise isolate equipment/machines from one or more power sources in a predictable, reliable manner. In some environments, such as industrial environments, more specialized types of isolation systems are often employed not only to control the delivery of power, but also to do so in a manner that reduces the chance that the controlled equipment/machines might be unintentionally restarted at times when they are being accessed by repair personnel or technicians for purposes of repair or modification. The use of such power delivery systems thus enhances the confidence and rapidity with which such personnel can accomplish such repairs/modifications.
Referring to FIG. 1, one Prior Art power delivery system of this type is the ElectroGuard™ Bulletin 2030 Safety Isolation System available from Rockwell Automation, Inc. of Milwaukee, Wis., the beneficial assignee of the present application. This power delivery system, shown in FIG. 1 as an isolation system 2, includes both an electrical power isolation system 4 and a pneumatic (or hydraulic or other fluidic) power isolation system 6, and operates as follows.
When a failure or other condition occurs at a machine 8 of an industrial system 10 (in this case, an assembly line), and an operator appropriately switches or triggers a remote lockout switch (RLS) 12 associated with that machine to an “OFF” position, the isolation system 2 serves to disconnect both electric power and pneumatic power lines 15 and 16, respectively, from the machine so as to decouple the machine from both of those types of power. Additionally, the isolation system 2 then further serves to ground the power wires to the machine 8.
Once the machine 8 has been isolated in this manner, an indication is provided to the operator (e.g., a light 18 turns on) indicating that it is appropriate for the operator to access the machine for purposes of making a repair or some other modification to the machine. Typically the operator will then access the machine by entering into a normally-inaccessible region, e.g., by opening a safety gate 20 and entering into the machine as shown (alternatively, for example, the operator could pass through a safety or safety presence sensing device).
Once the operator has completed the repair or modification and left the normally-inaccessible region, the operator appropriately switches or triggers the RLS 12 again, this time to an “ON” position. After this occurs, the isolation system 2 reestablishes the connections between the power sources and the machine 8. The isolation system 2 typically employs redundant circuitry such as safety relays to enhance the isolation system's reliability in performing its various functions.
Power delivery systems such as the isolation system 2 of FIG. 1 are often operated alongside other control systems that are employed to govern the operation of the controlled equipment/machines. In industrial environments, for example, programmable logic controllers (PLCs) are often employed to monitor and control the operation of the equipment/machines of an industrial system. Thus, as also shown in FIG. 1, the isolation system 2 can operate alongside a PLC 22, with the isolation system governing whether power (of various types) is provided to the machine 8 and the PLC 22 controlling operation of the machine 8 when power is being provided.
Notwithstanding the fact that power delivery systems are commonly employed alongside other control systems in controlling a variety of equipment/machines in industrial and other environments, conventional arrangements of such systems do not necessarily achieve optimal results under all circumstances. Rather, there are circumstances in which the operation of a power delivery system can negatively (however, unintentionally) impact the operation of equipment/machines that are under the control of an affiliated control system, insofar as the operation of the power delivery system undermines or conflicts with the operation of the affiliated control system.
For example, there are circumstances in which a control system is operating a machine to achieve a particular goal, and where an abrupt interruption of power to the machine will impede attainment of that goal. Further for example, with reference again to FIG. 1, if the PLC 22 was controlling the machine 8 to manufacture a given component part, an abrupt interruption of the power being provided to the machine 8 due to operation of the isolation system 2 could result in the cessation of the manufacturing process and possibly result in the creation of a partially-completed part that was neither saleable nor salvageable.
Additionally for example, abrupt interruptions of power (or switching on and off of power) can reduce the operational efficiency of machines such as the machine 8 that are being controlled by a control system such as the PLC 22. Such reductions in efficiency can occur, also for example, because the power interruptions disrupt the timing of the overall manufacturing process, because material or energy is wasted, or for other reasons. In extreme cases, abrupt interruptions of power can potentially even result in damage to machinery.
For at least these reasons, therefore, it would be advantageous if an improved manner of implementing power delivery systems that operate alongside other control systems in relation to controlled equipment/machines could be developed. More particularly, in at least some embodiments, it would be advantageous if an improved manner of implementing an overall system including each of an isolation system, an additional control system, and a controlled machine could be developed. In at least some such embodiments, it further would be advantageous if such overall systems continued to afford high levels of reliability as do many conventional isolation systems and/or control systems.